Sand Spit Morphology at an Inlet on Phu Quoc Island, Vietnam

Abstract

Tidal inlets with attached sand spits are a very common coastal landform. Since the evolution of sand spits along coastlines influence the social-economic development of local coastal areas, sand spits have become the objects of numerous studies. However, previous studies have mainly focused on sand spits that are usually in the scale of hundreds of meters in width, whilst knowledge about the evolution of smaller-scale sand spits still remains limited. Therefore, in this study, the morphological change of a small and unexplored sand spit in front of Song Tranh Inlet on the west coast of Phu Quoc Island, Vietnam is investigated. Satellite images are first used to observe the morphological change of the sand spit and calculate the longshore sediment transport rates (LSTR) along the sand spit. Waves and beach sediments are collected at the study site to calculate the longshore sediment transport rate using the CERC formula. It is found that there is a seasonal variation in the evolution of the sand spit at Song Tranh Inlet. The longshore sediment transport rates along the spit calculated by image analysis are 39,000 m3/year, 66,000 m3/year, and 40,000 m3/year, whilst the longshore sediment transport rate calculated by the CERC formula is 72,000 m3/year. This study aims to contribute to the methodology for investigating the evolutions of small sand spits and, specifically, sustainable coastal management for Phu Quoc Island, which is well-known as the Pearl Island of Vietnam.

Coastal Erosion Caused by River Mouth Migration on a Cuspate Delta: An Example from Thanh Hoa, Vietnam

“…Landsat imagery has been applied intensively in coastal studies, especially in areas with significant shoreline temporal variations, such as the mouths of rivers, sand spits, and around coastal structures [27,[30][31][32][33][34]. In this research, Landsat images spanning the period 1987 to 2023 were gathered (as shown in Table 1) to monitor alterations in the shorelines surrounding the mouth of the Ma River.…”

“…The along-shore and cross-shore coordinates of the cuspate tips on both sides of the mouth of the Ma River were observed and are used for discussing the morphological be havior of the river's mouth. The method of using the coordinates of special points such as the tips of sand spits or the center of gravity to discuss the evolution of a sand body has been applied widely in coastal engineering [27,30,32,34,44,45]. Figure 6 illustrates the schematic for measuring the coordinates of the cuspate tips, which are considered the most prominent protrusions into the open water.…”

Littoral Drift Impoundment at a Sandbar Breakwater: Two Case Studies along the Bight of Benin Coast (Gulf of Guinea, West Africa)

“…The offshore wave data extracted from the WaveWatch III model [43] were transformed to the nearshore using the COASTEXCEL tool [60]. Duy et al [61] applied and validated the wave transformation tool at the Phu Quoc island in Vietnam, which showed good agreement with measured datasets. Furthermore, inaccuracies in estimating the depth of closure may also arise from Equation ( 6) coefficients, wave reanalysis products, and coastal structures' presence [62][63][64].…”

Coastal Erosion Caused by River Mouth Migration on Cuspate Delta: An Example from Thanh Hoa, Vietnam

“…Landsat imagery has been applied intensively for coastal studies especially in areas with significant temporal variation of the shorelines such as as river mouths, sand spits, and around coastal structures [26][27][28][29][30][31]. In this study, Landsat images from 1987 to 2023 were collected (Table 1) for mapping the changes of the shorelines around the Ma River mouth.…”

“…In this section, the along-shore and cross-shore coordinates of the cuspate tips on both sides of Ma River mouth will be measured and used for discussing the morphological behavior of the river mouth. The method of using the coordinates of special points such as sand spit's tips or the central of gravity to discuss the evolution of a sand body has been applied widely in coastal engineering [26,28,29,31,41,42]. Figure 5 illustrates the schematic for measuring the coordinates of the cuspate tips, which are considered as the most prominent protrusions into the open water.…”